class_docstr: a immutable object holding a source code fragment,
  possibly deindenting it.
code: def __str__(self):
      return "\n".join(self.lines)
  
imports: from __future__ import generators
  from bisect import bisect_right
  import sys
  import inspect, tokenize
  import py
  from types import ModuleType
label_desc: Use image node_id 13 for calling the Source obj's underlying member method code with example usage: obj.__str__() and returns: str